function whose arguments contains a function with possibly a variable number of outputs

Question

Alain Barraud 2021-8-31

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1444184-function-whose-arguments-contains-a-function-with-possibly-a-variable-number-of-outputs

评论： Alain Barraud 2021-9-1

I am writing a class which calls matrix and vector matlab functions adding some stuff to obtain an approximation of the number of significant bits.

For example with A=hilb(10) whose condition number is about 1e13 if I compute det(A) A beeing an object of my class I obtain 2.1640e-53 the number of displayed digits is automatically limited to the expected correct ones. To achive this I overload matlab function as shown below:

%%%%
methods
        function C=mldivide(A,B), C=rfpa.OP(@mldivide,A,B);end
        function d=det(A), d=rfpa.OP(@det,A);end
        function B=inv(A), B=rfpa.OP(@inv,A);end
        function c=cond(A), c=rfpa.OP(@cond,A);end
    ......
%%%

OP is a static method :

function xr=OP(fun,varargin)
            x1=fun(varargin{:});
            xr=zeros(size(x1),'rfpa');
            .....

This works fine but I have not found how to do, when function has a variable number of outputs as QR SVD for example.

Is it possible to implement something like

function varargout=OP(fun,varargin)
    [varargout{1:nargout}]=fun(varargin{:});
    .....

My current solution is to have specific wrapper for QR SVD etc... which is no intellectually satisfactory.

Any help will be welcome.

Alain

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Answer 1

Steven Lord 2021-8-31

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https://ww2.mathworks.cn/matlabcentral/answers/1444184-function-whose-arguments-contains-a-function-with-possibly-a-variable-number-of-outputs#answer_778139

See this documentation page, specifically the section on How to Use Comma-Separated Lists.

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Alain Barraud 2021-9-1

OK, According to the Function Return Values example it is necessary to add nargout as a input parameter within my function OP. Now it works as expected.

Thanks a lot

Alain

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